Ōshima Chizuru (大島 千づる, lit. Chizuru Ōshima) is a first year student at Syoyo High School.
Although Oshima is timid and lacks confidence she is said to be a cute girl.
She wears the regular gakuran, a reddish brown jacket over a cream school sweatshirt and a white shirt with a light blue tie. She wears a black miniskirt checkred with grey lines, on her feet she wears middle-length black socks and the required brown shoes.
She is very shy, a little pessimistic and timid, and even though she likes Haru, she always gives him advice when he can't understand Shizuku. She's also very quiet, kind and most of the time has a gentle way of saying things. Whenever she says vulgar things such as asking Haru if he "has the balls" to confess his feelings for Shizuku, she feels greatly embarrassed for losing her temper. She is in the same class as Haru in the second year, and the class appoints her as the person to discipline and control Haru.
Chizuru is best known as a silent and timid girl in class and as seen in the anime, she notes that being inside a classroom filled with people makes her feel useless. Although she is not so popular, she is a class representative, admitting to Yoshida that she might have been elected because of her glasses. She tends to avoid minimal conversation and conflict by being a pushover to her classmate.
She was first introduced in the anime when she asked her classmates to help her set up for Sports Day. They nonchalantly reject her and she quickly tells them that she'll set up by herself. While setting up for Sports Day, she accidentally hits an upperclassman in the head with a volleyball pole she was holding. When he kicked her down and told her how unwanted she is, it fueled Yoshida Haru's anger and he fought an upperclassman for bullying her. 
It was revealed that she is her classroom's class representative. She is unpopular and invisible, beause she attended school after her hospitalisation was completed and before she could make any friends, people had already fomed their little cliques.
She then discovers her deep interest in Haru when she begins to talk with him, admitting to herself and her friend, Yuu-chan, that she's fallen in love. Chizuru thanked Haru for standing up for her one day in the locker room which secretly triggered Shizuku's jealousy instinct. Asako Natsume brought up Chizuru as a possible rivalry and Sohei Sasahara even input that Chizuru is a quiet, but cute girl. Shizuku coldly brushed it off her shoulders without showing a bit of interest, but secretly hid whenever Chizuru and Yoshida spoke with each other.
She starts hanging out with Shizuku's group of friends after Yoshida found her eating alone on a flight of stairs. She desperately wants to tell Yoshida how she felt about him, but would always become interrupted when Yoshida brought up Shizuku. She finally realises that Yoshida is in love with Shizuku with the help of Asako's bluntness, and that Shizuku feels the same way. Despite her constant encourgement she gives Haru to pursue Shizuku, she still has high hopes of trying to pursue Haru herself. Haru is oblivious to Chizuru's feelings except for Asako, who blatantly tries to tell Haru that he should always try with Shizuku no matter how unresponsive she is.
During the festival, Yoshida asked Chizuru what she would do if he was to confess that he liked her while Yamaguchi and Shizuku is in the same room, all four hiding from Yoshida's older brother, Yuuzan. Chizuru thought it was an honest confession, when Yoshida laughed it off and told her it was all a joke. Chizuru decided that she should tell him how she really felt, and in the midst of her confession, Shizuku tries to unsuccessfully escape causing embarrassment and shock from both parties. Since then, Chizuru distanced herself from Haru but still cannot seem to pull her feelings away.
They first met when Yoshida Haru stood up for Chizuru after an upperclassman kicked her down during Sports Day. Chizuru was oblivious to what was going on between Yoshida and Shizuku until she overheard her fellow classmates fawn over Yoshida from afar, asking if there was something going on between "the girl that's always with Yoshida." Chizuru decided to find out for herself when she asked Yoshida if Natsume was a nice girl, and then Mizutani-san. Haru bluntly tells Chizuru that he loves Shizuku, but Chizuru didn't understand if he meant it as a romantic way or as a friendship way. She decides to persist her curiosity and asks if he loves Shizuku romantically, but was interrupted when Asako Natsume showed up to the scene looking for Yoshida Haru.
When Chizuru started hanging out with the group more, Haru would always confide in Chizuru how much he loves Shizuku and the problems he has to endure due to their complicated status. As much as Chizuru saw this as an opportunity to pursue Haru for herself, she gives Haru words of encouragement and perspective or sensibility.
During the festival, she tried to confess to Haru about her feelings not knowing that Yamaguchi Kenji and Mizutani Shizuku were hiding in the same room behind some desks and boxes. Haru laughed it off and told her that he thought she was swell, but makes it clear to her that he loves Shizuku. Chizuru loves Haru, but is either too shy to go against Shizuku or is too respectful to go against her. Either way, she slowly distances herself despite her feelings.
Yuu-chan, as Chizuru calls her, is her friend that she constantly texts at school. Miyama Yuu didn't make an appearance until episode 10 of the anime. She is Chizuru's long term friend, and also a past school mate. Chizuru was supposed to enter the same high school as Yuu-chan, but because she became hospitalised, she attended a different school and endured struggles of having to fit in and find friends. Miyama is often seen texting Chizuru slang and funny puns to lighten up the atmosphere.
Chizuru and Shizuku don't talk much on a regular basis, and don't even greet each other to acknowledge the other person's presence. It is subliminally suggested that Chizuru is slightly intimidated by Shizuku, especially with her cold exterior and her ability to keep Yoshida Haru so keen on her. Chizuru doesn't view Shizuku as a rival, because she gets the hint that Shizuku and Haru has had something much before Chizuru came into the scene. Although Shizuku is slightly jealous of Chizuru and secretly sees her as a threat, Shizuku keeps her feelings bottled up, which resulted in her slipping to #29 on the academic charts. Chizuru is either always in the middle of an argument between Shizuku and Haru, keeping her distance, or comforting Haru after he tells her the troubles of dealing with Shizuku. There friendship also began to grow after Haru's departure and hang out often with her friends. They get along well with each other as they remain friends.
Asako met Chizuru on a flight of stairs one day during lunch while Chizuru asked Haru about Shizuku. Asako initially thought that it was a confession, when Haru casually explains that they were just talking about Natsume and the entire crew. He nonchalantly tells Asako Natsume that Chizuru has no friends, and right away, Asako took Chizuru's hands into hers and told her that she'd be Chizuru's friend.
Chizuru and Sasayan don't speak much, but Sasayan is always nice enough to pursuade Chizuru to be included in friendly events such as the Christmas party at the Batting Centre.
Takaya is Shizuku's younger brother. He is infatuated with Chizuru and becomes especially needy when she's around, dragging her everywhere he goes to spend more time with Chizuru. Chizuru does not know it and sees Takaya as a cute, younger brother. In the last volume she is kissed by Takaya.
He confesses to her before the wedding and she did not intend to accepted his feelings.
- Her blood type is A.
- Ōshima is worried about being a boring person.
- Ōshima's family runs a kimono store.
- "...Do you have any balls!?"
- "Why is everything an error...I want back to the elementary school!"
- "Yuu-chan... I think I'm in love."
- "Damn it, why do I always ask questions that'll only depress me more?"
- "E-e-e-eh?! She might as well tell him that she loves her!"
- "W-what?! ...So, what would you say if I told you that I liked you? Not in a friendship way! I-In a female attracted to male way!!"
- "... Sigh... It's Oshima, not Oyama..."
- "I-I didn't mean to thank you the other day! S-s-s-so, thank you for standing up for me"
|Maki • Kyoko Misawa • Yū Miyama • Shizuku Mizutani • Yoshino Mizutani • Asako Natsume • Natsume's Ex-Colleagues • Saeko Ninomiya • Yamase • Chizuru Ōshima|
|Andou • Haru's Father • Issei Joujima • Kitano • Masahiro Ayanokouji • Mitsuyoshi Misawa • Mizutani Takashi • Takaya Mizutani • Samejima • Sōhei Sasahara • Seda • Shimoyanagi • Ryuuji Tomioka • Kenji Yamaguchi • Haru Yoshida • Yuuzan Yoshida|
|Dog • Mimi • Nagoya • Shizuku's Golden Fish|